R round to nearest .5 or .1

Question

I have a data set of stock prices that have already been rounded to 2 decimal places (1234.56). I am now trying to round to a specific value which is different

Answer 1

I'm not familiar with R the language, but my method should work with any language with a ceiling function. I assume it's rounded UP to nearest 0.5:

a = ceiling(a*2) / 2

if a = 0.4, a = ceiling(0.4*2)/2 = ceiling(0.8)/2 = 1/2 = 0.5
if a = 0.9, a = ceiling(0.9*2)/2 = ceiling(1.8)/2 = 2/2 = 1